(1) Field of the Invention
The present invention relates to an improved method for the conversion of malic acid to lactic acid (malolactic fermentation) in wine. In particular the present invention relates to an improvement wherein the wine is inoculated directly with specially activated bacteria.
(2) Prior Art
Various methods have been devised for removing malic acid from wine. The removal involves the conversion of dicarboxylic L-malate to the monocarboxylic L-lactate with the resulting loss of one carboxyl acid group, so that the acidity of the wine is decreased. In certain instances the use of Leuconostoc species, Pediococcus species or Lactobacillus species for the malolactic fermentation has been suggested; however, the initial high acidity of the wine prevents a significant reduction of the amount of malic acid by the bacteria. The prior art methods are described in U.S. Pat. No. 4,380,552 to Gestrelius as well as in U.S. Pat. No. 2,080,138, 4,350,708, 3,843,809, 2,415,431. In the Gestrelius et al method, Leuconostoc oenos are protected by an alginate gel and the wine is percolated through the gel in the malolactic fermentation. This method is slow and is believed to be even less satisfactory in terms of malic acid reduction than a direct inoculation of the wine with the bacteria.
Other prior art which describes the inoculation of wine with bacteria includes Beelman R. B., et al. Symposium: Microbiology and Wines Chapter 9, 107 to 121 (1982); Beelman, R. B., et al. Am. Journal of Enology and Viticulture 31 269-276 (1980); Gallander, J. F., Am. J. Enol. and Vitic. 30, 157-159 (1979); Kunkee, R. E., Am. J. Vitic 18, 71-77 (1967) Beelman, R. B. et al., Am. J. Enol and Vitic 21, 193-200 (1970); Kunkee, R. E., et al., Am. J. Enol. and Vitic. 15, 178-183 (1964); Pilone, G. J., Am. J. Enol. and Vitic. 30 326 (1979); Mayer, K. et al., Die Weinwirtschaft 9 223-226 (1979); King, S. W., Masters Thesis, Pennsylvania State University, (Shelved 1982); Beelman, R. B., et al., Am. J. Enol. Vitic. 28, 159-165 (1977); Kole, M., et al., Biotechnology Letters 4, 695-700 (1982); Beelman, R. B., et al., University of California at Davis, Grape and Wine Centennial Symposium Proceedings 109-117 (1982); Hayman, D. C., Food Technology in Australia 34, 14-18 (1982); Lafon-Lafourcade, S., et al., Anton. Leeyvenhoek J. Microbiol. 49, 349-352 (1983); Silver, J., et al Am. J. Enol. Vitic. 32, 64-72 (1981). None of these methods are completely reliable.